Abstract: The attacks on the World Trade Center (WTC) on 9/11/2001 (9/11) involved collision of two aircraft into the buildings and the combustion of many thousands of pounds of jet fuel. The subsequent collapse on the towers, and the rescue/recovery effort that followed, led to large numbers of responders being exposed to a wide variety of hazardous material including pulverized cement, glass, asbestos, lead, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorine pesticides, and polychlorinated furans and dioxins (1-3). Three research centers that follow cohorts of rescue and recovery workers since the WTC disaster include the Fire Department of the City of New York (FDNY); the Icahn School of Medicine at Mount Sinai (ISMMS); and the New York City Department of Health and Mental Hygiene (DOHMH). Modest though mostly non-statistically significantly elevated cancer rates post-exposure to the WTC-site have been reported in all three of the cohorts, despite limited follow-up time since 9/11/2001 (4-7). We propose to combine these three cohorts to account for individuals who are in more than one cohort, to increase the sample size, and to make the results more generalizable. We plan to update the incidence findings from the prior reports using consistent exposure and outcome definitions and taking advantage of the additional six years of follow-up since those publications. We also plan to study the time elapsed from WTC- exposure to increased incidence of WTC-associated cancer. We believe that this short-term high intensity exposure with long-term follow-up in responder cohorts, combined for these analyses, offers a rare opportunity to investigate cancer latency in humans. Finally, we also propose the first study of cancer survival in WTC rescue/recovery workers with cancer.